Ai no DNA

Ever since he was young, Miharu has suffered from phantom pains. When his divorced parents decide to reunite after 15 years of separation, he discovers the exact reason why: his younger brother, Natsu. Apparently, he and his brother are astrological twins. Miharu feels Natsu's pain, but... Natsu doesn't feel Miharu's? That's just not fair!
(from B-U)